The invention relates to a method and an apparatus for casting filaments of superalloys. More particularly, the invention relates to a method and an apparatus for casting filaments of superalloys using a high pressure differential furnace and mold system.
Weld wires are typically required for repair of aircraft components that have been in service for a period of time. The weld wires employed for repair of aircraft components include high performance alloys or superalloys, such as, for example, Rene 142, Rene N4, or Rene N5. These single crystal superalloy materials are directionally solidified and provide the advantages of increased strength and higher oxidation resistance in comparison to traditional alloys. However, the superalloy materials typically include a large number of alloying elements or metals, which makes these materials difficult to process into small diameter filaments employed as weld wires. Accordingly, using conventional casting techniques and systems, superalloy ingots having a minimum diameter of ˜0.2 inches are typically produced. Further, superalloy ingots cast using conventional casting techniques typically include defects, such as, shrinkage, cold shuts, or cold laps.
These ingots may be then further processed using thermomechanical processing, such as, extrusion and swaging. This is followed by grinding or some other form of finishing or machining. However, the thermomechanical processing approach is expensive, the cycle times are long, and sophisticated thermomechanical processing equipment may be required.
Thus, there is a need to provide a method and apparatus that allows for cost-effective and on-demand production of superalloy filaments or weld-wires. Further, there is a need to provide a method and apparatus for forming small diameter and high aspect ratio superalloy filaments or weld-wires having minimal defects.